Internal combustion engine with variable effective length connecting rod

ABSTRACT

An internal combustion engine may include a cylinder block defining a cylinder, and a crankshaft defining a crankpin, wherein the crankshaft is rotatably received by the cylinder block and rotates about a longitudinal axis. The internal combustion engine may further include a piston configured to reciprocate within the cylinder, and a connecting rod operably coupled to the piston and the crankpin. The connecting rod may include a first rod element having a first distal end and a first proximate end, wherein the first distal end is operably coupled to the piston. The connecting rod may further include a second rod element having a second distal end operably coupled to the first proximate end of the first rod element, and a second proximate end operably coupled to the crankpin, wherein the first rod element and the second rod element are pivotally coupled to one another.

RELATED APPLICATIONS

This application is a divisional and claims the benefit of U.S. patentapplication Ser. No. 12/850,674, filed Aug. 5, 2010, which claims thebenefit of priority under 35 U.S.C. §119(e) of U.S. ProvisionalApplication No. 61/231,812, filed Aug. 6, 2009, the disclosures of bothof which are incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to internal combustion engines. Inparticular, the present disclosure relates to internal combustionengines with improved fuel efficiency and/or power output.

BACKGROUND

High fuel costs and a desire to reduce undesirable emissions associatedwith operation of internal combustion engines has renewed interest inimproving fuel efficiency during operation. Thus, it may be desirable toimprove the efficiency of conventional internal combustion engines.

A conventional internal combustion engine includes a cylinder blockdefining journals for receiving a crankshaft and one or more cylindershousing a piston that is operably coupled to the crankshaft at acrankpin via a connecting rod. During conventional operation, the pistonreciprocates within the cylinder, such that during a power stroke of theinternal combustion engine, combustion of an air/fuel mixture within acombustion chamber defined by the piston and the cylinder forces thepiston toward the crankshaft. As the piston travels toward thecrankshaft, the crankshaft is rotated via the connecting rod andcrankpin, thereby converting the potential energy associated with theair/fuel mixture into mechanical work.

Due to the architecture of a conventional internal combustion engine,when the piston is at a position within the cylinder that coincides withthe maximum compression (i.e., the combustion chamber is at its lowestvolume when the piston is farthest from the crankshaft), the axis of theconnecting rod and the axis of the crankpin tend to be nearly co-linear,if not co-linear. At these relative positions, as the piston firstbegins its movement toward the crankshaft during the power stroke, thereis only a very short moment arm (if any) created between the axis of theconnecting rod and the axis of the crankpin. As a result, the forceinitially created by the air/fuel mixture at the moment of combustiondoes not transfer as much torque to the crankshaft as it would if thelength of the moment arm were greater. This situation may beparticularly undesirable because, during combustion and very shortlythereafter, the force on the piston due to the combustion eventapproaches its maximum magnitude. Further, as the piston travels downthe cylinder toward the crankshaft and the length of the moment armincreases, the magnitude of the force from the combustion event actingon the piston dissipates rapidly. Thus, because there is a very shortmoment arm created between the axis of the connection rod and the axisof the crankpin during the time of maximum force on the piston,efficiency of the work generated from the combustion process may be lessthan desired.

Thus, it may be desirable to provide an internal combustion engine witha configuration that improves the efficiency and/or increase poweroutput of the internal combustion engine during operation. Further, itmay be desirable to provide an internal combustion engine with aconfiguration that permits tailoring of desired performancecharacteristics.

SUMMARY

In the following description, certain aspects and embodiments willbecome evident. It should be understood that the aspects andembodiments, in their broadest sense, could be practiced without havingone or more features of these aspects and embodiments. It should beunderstood that these aspects and embodiments are merely exemplary.

One aspect of the disclosure relates to an internal combustion engine.The internal combustion engine may include a cylinder block defining acylinder, and a crankshaft defining a crankpin, wherein the crankshaftis rotatably received by the cylinder block and rotates about alongitudinal axis. The internal combustion engine may further include apiston configured to reciprocate within the cylinder, and a connectingrod operably coupled to the piston and the crankpin. The connecting rodmay include a first rod element having a first distal end and a firstproximate end, wherein the first distal end is operably coupled to thepiston. The connecting rod may further include a second rod elementhaving a second distal end operably coupled to the first proximate endof the first rod element, and a second proximate end operably coupled tothe crankpin, wherein the first rod element and the second rod elementare pivotally coupled to one another.

According to another aspect, an internal combustion engine may include acylinder block defining a cylinder, and a crankshaft defining acrankpin, wherein the crankshaft is rotatably received by the cylinderblock and rotates about a longitudinal axis. The internal combustionengine may further include a piston configured to reciprocate within thecylinder, and a connecting rod operably coupled to the piston and thecrankpin, wherein the connecting rod has a first distal end operablycoupled to the piston and a second proximate end operably coupled to thecrankpin. The first distal end and the second proximate end define aneffective length of the connecting rod, and the connecting rod isconfigured such that the effective length of the connecting rod isvariable.

According to still a further aspect, a power train may include aninternal combustion according to any of the exemplary embodimentsdescribed herein, a transmission operably coupled to the engine, and adrive member configured to perform work, wherein the drive member isoperably coupled to the transmission.

According to yet another aspect, a vehicle may include an internalcombustion according to any of the exemplary embodiments describedherein, a transmission operably coupled to the engine, and a drivemember configured to perform work, wherein the drive member is operablycoupled to the transmission.

Additional objects and advantages of the disclosure will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the disclosedembodiments.

Aside from the structural and procedural arrangements set forth above,the embodiments could include a number of other arrangements, such asthose explained hereinafter. It is to be understood that both theforegoing description and the following description are exemplary only.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this description, illustrate several exemplary embodiments andtogether with the description, serve to explain the principles of theembodiments. In the drawings,

FIG. 1 is a schematic partial perspective view of an exemplaryembodiment of an internal combustion engine;

FIG. 2 is a schematic partial perspective view of a portion of theexemplary embodiment shown in FIG. 1;

FIG. 3 is a schematic side view of an exemplary embodiment of acrankshaft for the exemplary engine;

FIG. 4A is a schematic partial perspective view from a first perspectiveof a portion of the exemplary embodiment shown in FIG. 1;

FIG. 4B is a schematic partial perspective view from a secondperspective of a portion of the exemplary embodiment shown in FIG. 1;

FIG. 5 is a schematic side view of the exemplary embodiment shown inFIG. 1;

FIG. 6 is a schematic perspective section view of the exemplaryembodiment shown in FIG. 1;

FIG. 7 is a schematic end section view of the exemplary embodiment shownin FIG. 1 with a radial axis angle of a crankshaft shown at 0 degrees;

FIG. 8 is a schematic end section view of the exemplary embodiment shownin FIG. 1 with the radial axis angle of the crankshaft shown at 15degrees;

FIG. 9 is a schematic end section view of the exemplary embodiment shownin FIG. 1 with the radial axis angle of the crankshaft shown at 31degrees;

FIG. 10 is a schematic end section view of the exemplary embodimentshown in FIG. 1 with the radial axis angle of the crankshaft shown at 45degrees;

FIG. 11 is a schematic end section view of the exemplary embodimentshown in FIG. 1 with the radial axis angle of the crankshaft shown at 60degrees;

FIG. 12 is a schematic end section view of the exemplary embodimentshown in FIG. 1 with the radial axis angle of the crankshaft shown at 90degrees;

FIG. 13 is a schematic end section view of the exemplary embodimentshown in FIG. 1 with the radial axis angle of the crankshaft shown at120 degrees;

FIG. 14 is a schematic end section view of the exemplary embodimentshown in FIG. 1 with the radial axis angle of the crankshaft shown at174 degrees;

FIG. 15 is a schematic end section view of the exemplary embodimentshown in FIG. 1 with the radial axis angle of the crankshaft shown at180 degrees;

FIG. 16 is a schematic end section view of the exemplary embodimentshown in FIG. 1 with the radial axis angle of the crankshaft shown at270 degrees; and

FIG. 17 is a schematic end section view of the exemplary embodimentshown in FIG. 1 with the radial axis angle of the crankshaft shown at0/360 degrees.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to exemplary embodiments. Whereverpossible, the same reference numbers are used in the drawings and thedescription to refer to the same or like parts.

FIGS. 1-17 schematically illustrate an exemplary embodiment of aninternal combustion engine 10. In the exemplary embodiment shown,exemplary engine 10 is a reciprocating-piston internal combustionengine. As shown in FIG. 1, engine 10 includes a cylinder block 12defining a number of cylinders 14, each defining a longitudinal axis CL.In the exemplary embodiment shown, engine 10 has an in-lineconfiguration and four cylinders 14 a, 14 b, 14 c, and 14 d. Althoughexemplary engine 10 has a configuration commonly referred to as an“in-line four” configuration, engine 10 may have other configurationsknown to those skilled in the art, such as, for example, configurationscommonly referred to as “V,” “W,” “H,” “flat,” “horizontally-opposed,”and “radial.” Further, although exemplary engine 10 has four cylinders,engine 10 may have other numbers of cylinders known to those skilled inthe art, such as, for example, one, two, three, five, six, eight,twelve, sixteen, twenty, and twenty-four. Thus, engine 10 may have, forexample, any one of configurations commonly referred to as “flat-four,”“flat-six,” “in-line six,” “straight-eight,” “V-8,” “V-10,” “V-12,”“W-12,” and “H-16.” Further, although exemplary engine 10 is describedherein in relation to four-stroke operation, other operations known tothose skilled in the art are contemplated, such as, for example,two-stroke, three-stroke, five-stroke, and six-stroke operation.

As shown in FIG. 1, exemplary engine 10 includes pistons 16corresponding to cylinders 14, for example, four pistons 16 a, 16 b, 16c, and 16 d (see FIGS. 1 and 2). As shown in FIG. 1, pistons 16 a and 16d are positioned in the upper end (i.e., “upper” being relative to theorientation of engine 10 shown in FIG. 1) of cylinders 14 a and 14 d,respectively, while pistons 16 b and 16 c are not visible in FIG. 1 dueto being positioned lower in the cylinders 14 b and 14 c, respectively(see FIG. 2). To the extent that the relative positions of the pistons16 in the cylinders 14 indicate a relative firing order of engine 10(i.e., the sequential order of combustion events as identified bycylinders), exemplary engine 10 may be configured to have a differentfiring order, as is known to those skilled in the art.

Cylinder block 12 of exemplary engine 10 defines a number of bearingsfor receiving a crankshaft 20 (see FIG. 3), such that crankshaft 20 mayrotate relative to cylinder block 12 about a longitudinal axis CSdefined by crankshaft 20. For example, as shown in FIG. 3, crankshaft 20defines a number of journals 22 corresponding to the number of bearings(not shown) defined by cylinder block 12, and journals 22 are receivedby bearings, such that crankshaft 20 may rotate about longitudinal axisCS.

Exemplary crankshaft 20, as shown in FIG. 3, also defines a number ofcrankpins 24 corresponding to the number of pistons 16. Crankpins 24 arecircular in cross section, and the respective circular cross-sectionsmay define a center C (see, e.g., FIGS. 6 and 7), which, in turn,defines a longitudinal crankpin axis CP extending in a perpendicularmanner through center C of the cross-section of the respective crankpin24, such that crankpin axis CP is parallel and offset with respect tocrankshaft axis CS. For example, crankpin axis CP is spaced a distance T(see FIG. 7) from the longitudinal axis CS of crankshaft 20. Crankshaft20 may also include a number of counterbalance weights 26 for providing(or improving) rotational balance of crankshaft 20 when assembled withpistons 14 and connecting rods.

Referring to FIGS. 4A and 4B, in exemplary engine 10, pistons 16 areoperably coupled to crankshaft 20 via a number of connecting rods 28corresponding to the number of pistons 16. In particular, exemplaryconnecting rods 28 include a first rod element 28 a and a second rodelement 28 b. According to some embodiments, first rod element 28 a isslightly curved (i.e., downward and to the left as shown in FIGS. 4A and7-17) in order to provide clearance with internal surfaces of cylinderblock 12. According to some embodiments, first rod element 28 a isstraight and cylinder block 12 may be configured to provide clearancefor first rod element 28 a.

In the exemplary embodiment shown in FIGS. 4A and 4B, a distal end 30 offirst rod element 28 a defines a first end aperture 32 (see FIGS. 7-17)for operably coupling first rod element 28 a of connecting rod 28 topiston 16 via, for example, a pin 38. A distal end 40 of second rodelement 28 b is operably coupled to a proximate end 42 of first rodelement 28 a, and a proximate end 44 of second rod element 28 b isoperably to crankshaft 20 at crankpin 24. First rod element 28 a andsecond rod element 28 b are coupled to one another such that first rodelement 28 a and second rod element 28 b are permitted to pivot withrespect to one another. For example, first rod element 28 a and secondrod element 28 b are coupled to one another via a pin 46 such that theyare coupled to one another in a hinge-like manner.

According to the exemplary embodiment shown, second rod element 28 bincludes two plates 48 a and 48 b that sandwich first rod element 28 a(see FIGS. 4A and 4B). Pin 46 extends between plates 48 a and 48 bthrough first rod element 28 a, thereby operably coupling plates 48 aand 48 b to one another and to first rod element 28 a. Exemplary plates48 a and 48 b include apertures 50 configured to receive crankpin 24 ofcrankshaft 20. Thus, first rod element 28 a and second rod element 28 bserve to operably couple crankpin 24 of crankshaft 20 to piston 16, andfirst rod element 28 a and second rod element 28 b, by virtue of beingpivotally coupled to one another in a hinge-like manner, can effectivelyalter the distance between the center C of crankpin 24 and piston pin 38(i.e., connecting rod 28 has a variable effective length).

According the exemplary embodiment shown (see, e.g., FIGS. 6 and 7,which are schematic section views taken along line 6-6 of FIG. 5),engine 10 includes a surface 52 associated with an interior of cylinderblock 12. Exemplary surface 52 is configured to cooperate with secondrod element 28 b such that pivoting motion of first rod element 28 arelative to second rod element 28 b may be affected (e.g., at leastpartially controlled). Thus, the cross-sectional profile of surface 52and/or the configuration of second rod element 28 b may be configured toincrease efficiency and/or increase power output of engine 10.

As shown in FIGS. 4A and 4B, exemplary second rod element 28 b includestwo followers 54 a and 54 b configured to contact, either intermittentlyor continuously, surface 52 as crankshaft 20 rotates (e.g., see FIGS.7-17), thereby affecting the pivoting motion between first rod element28 a and second rod element 28 b. As explained in more detail herein,affecting the pivoting motion between first rod element 28 a and secondrod element 28 b may affect the effective length of connecting rod 28(i.e., the distance between crankpin 24 and pin 38, which connects firstrod element 28 a and piston 16 to one another). One or more of followers54 a and 54 b may be, for example, a roller follower. Although theexemplary embodiment shown includes two followers, other numbers offollowers are contemplated, including, for example, one or threefollowers. Further, types of followers other than roller followers arealso contemplated.

Exemplary surface 52 may be defined by an interior surface of cylinderblock 12 and/or a cam member operably coupled within cylinder block 12.For example, the interior surface of cylinder block 12 may define across-sectional profile 56 that may include one or more rectilinearand/or curvilinear portions, such as exemplary curvilinear portions 58a, 58 b, and 58 c, and rectilinear portion 58 d, as shown in FIGS. 7-17.As mentioned above, cross-sectional profile 56 may be tailored tocooperate with followers 54 a and/or 54 b of second rod element 28 b,such that efficiency and/or power output of engine 10 may be increased.

According to some embodiments, a portion, or the entirety, of surface 52may be provided by an insert operably coupled within cylinder block 12.For example, at least a portion of surface 52 may be formed on a cammember (not shown) that is operably coupled within cylinder block 12.According to some embodiments, the cam member may be configured suchthat its orientation relative to cylinder block 12 may be altered and/orthe cross-sectional profile of the cam member may be altered, forexample, during operation of engine 10. Such alteration(s) may beimplemented, for example, hydraulically, pneumatically, and/orelectrically (e.g., via solenoid operation). Such alterations may beused to facilitate alteration of interaction between surface 52 andsecond rod element 28 b (i.e., via exemplary followers 54 a and 54 b).Such embodiments may facilitate tailoring of engine operationcharacteristics, for example, to increase efficiency and/or power outputin response changing demands of engine operation due, for example, tochanging driving conditions of a vehicle in which engine 10 isoperating.

Exemplary engine 10 includes a travel limit assembly 60 configured tothe confine the length of the stroke of piston 16 between an extendedlimit and a contracted limit (see, e.g., FIG. 6). For example, travellimit assembly 60 includes a first limit member 62 and a second limitmember 64. First limit member 62 includes a distal end 66 operablycoupled to piston 16 and/or first rod element 28 a. Second limit member64 includes a proximate end 68 operably coupled to crankpin 24 ofcrankshaft 20 and a distal end 70 operably coupled to first limit member62. First limit member 62 and second limit member 64 are coupled to oneanother such that the length of travel limit assembly is variablebetween a minimum extent (see, e.g., FIG. 15) and a maximum extent (see,e.g., FIG. 7).

For example, as shown in FIG. 6, distal end 66 of first limit member 62defines an aperture 72 configured to receive pin 38 and be operablycoupled to piston 16 and/or distal end 30 first rod member 28 a. Firstlimit member 62 includes a tubular portion 74 extending from distal end66. Second limit member 64 includes a body portion 76 and a cap 78configured to be coupled to body portion 76 via, for example, bolts 80.Body portion 76 and cap 78 define an aperture 82 configured to receivecrankpin 24 of crankshaft 20. Exemplary body portion 76 includes anextension 84 configured to be received in tubular portion 74 of firstlimit member 62. In this exemplary configuration, first limit member 62and second limit member 64 are coupled to one another in a telescopingmanner. Extension 84 defines a stop 86, for example, a shoulder,configured to limit the extent to which extension 84 extends intotubular portion 74. According to an alternative embodiment (not shown),second limit member 64 may include a tubular portion and first limitmember 62 may be configured to extend into the tubular portion of secondlimit member 64.

In the exemplary embodiment shown, when assembled, connecting rod 28 andtravel limit assembly 60 are assembled in pairs corresponding to acommon piston 16 and a common crankpin 24 (see, e.g., FIGS. 4B and 6),such that each connecting rod-travel limit assembly pair is operablycoupled to the same piston 16 and the same crankpin 24. First rodelement 28 a of connecting rod 28 is configured to provide clearance fortravel limit assembly 60, such that travel limit assembly 60 can beoperably coupled to the same piston 16 as connecting rod 28 of theconnecting rod-travel limit assembly pair. For example, first rodelement 28 a defines a space 88 through which first limit member 62extends (see, e.g., FIGS. 4B and 6).

During operation of exemplary engine 10, as crankshaft 20 rotates,crankpins 24 revolve around crankshaft longitudinal axis CR, such thatcrankpin centers C define a circular path having a radius defined by thedistance T defined along a radial axis RA (see FIGS. 7-17) extendingbetween the longitudinal axis CS of crankshaft 20 and the longitudinalaxis CP of the respective crankpins 24. Thus, apertures 50 of second rodelement 28 b, which are rotatably coupled with respect to crankpins 24,also revolve about the crankshaft axis CS. Distal end 30 of first rodelement 28 a of connecting rod 28 is constrained to move in areciprocating and linear manner due to being operably coupled to pistons16, which are likewise constrained to move in a reciprocating and linearmanner within respective cylinders 14 defined by cylinder block 12. As aresult, as crankshaft 20 rotates, pistons 16 reciprocate withinrespective cylinders 14, defining a piston stroke generallycorresponding to twice the distance T between the crankpin axis CP andthe crankshaft axis CS.

During operation of a conventional engine, a piston reciprocates withinthe cylinder, such that during a power stroke of the internal combustionengine, combustion of an air/fuel mixture within a combustion chamberdefined by the piston and the cylinder (and cylinder-head (not shown))forces the piston toward the crankshaft. As the piston travels towardthe crankshaft, the crankshaft is rotated via the connecting rod andcrankpin, thereby converting the potential energy associated with theair/fuel mixture into mechanical work.

Due to the architecture of a conventional internal combustion engine,however, when the piston is at a position within the cylinder thatcoincides with the maximum compression (i.e., the combustion chamber isat its lowest volume, this condition coinciding with maximumcompression, when the piston is farthest from the crankshaft), the axisof the connecting rod and the axis of the crankpin tend to be nearlyco-linear, if not co-linear. At these relative positions, as the pistonfirst begins its movement toward the crankshaft during the power stroke,there is only a very short moment arm (if any) extending between theaxis of the connecting rod and the axis of the crankpin. As a result,the force initially created by the air/fuel mixture at the moment ofcombustion does not transfer as much torque to the crankshaft as itwould if the length of the moment arm were greater. This situation maybe particularly undesirable because, during combustion and very shortlythereafter, the force on the piston due to the combustion eventapproaches its maximum magnitude. Further, as the piston travels downthe cylinder toward the crankshaft and the length of the moment armincreases, the magnitude of the force from the combustion event actingon the piston dissipates rapidly. Thus, because there is a very shortmoment arm created between the axis of the connection rod and the axisof the crankpin during the time of maximum force on the piston,efficiency of the work generated from the combustion process in aconventional internal combustion engine may be less than desired.

Exemplary engine 10 is configured to employ a strategy that delays anysubstantial movement of piston 16 toward crankshaft 20 during the powerstroke, until crankshaft 20 has rotated to point at which there is amore effective moment arm between connecting rod axis CR and radial axisRA extending between crankshaft axis CS and a respective crankpin axisCP. As a result, a greater amount of the energy of the combustion eventmay be captured because the maximum force acting on piston 16 coincideswith a greater moment arm, thereby resulting in more torque atcrankshaft 20 during the power stroke.

FIGS. 7-17 schematically illustrate exemplary operation of engine 10having exemplary connecting rod 28 and exemplary travel limit assembly60, which serve to delay piston 16's travel at the beginning of thepower stroke of exemplary engine 10. In particular, by allowing firstrod element 28 a and second rod element 28 b to pivot relative to oneanother in a controlled manner, such that the distance between thecenter CP of crankpin 24 and the center of pin 38 (i.e., the effectivelength of connecting rod 28) may be selectively varied. Such anexemplary embodiment renders it possible to effectively hold piston 16in cylinder 14 at a substantially fixed position for a short period oftime, even as crankpin 24 continues to revolve around crankshaft 20'saxis CS as crankshaft 20 rotates. As a result, it is possible to holdpiston 16 at the point of highest compression in the combustion chamberwhile crankpin 24 revolves to a position in which there is an increasedmoment arm formed between an axis defined between pin 38, which operablycouples first rod element 28 a to piston 16, and pin 46, which operablycouples first rod element 28 a to second rod element 28 b. In thisexemplary manner, the delaying strategy outlined below may beimplemented.

For example, as shown in FIG. 7, crankshaft 20 is oriented such thatradial axis RA defined by the center of crankshaft 20 and the center ofcrankpin 24 is oriented at zero degrees, which corresponds generally afirst stroke termination angle θ₁ that generally coincides with the endof the compression stroke of exemplary engine 10. Thus, with radial axisRA in this orientation, piston 16 is at its upper position withincylinder 14.

As shown in FIG. 7, follower 54 a of second rod element 28 b is incontact with exemplary curvilinear portion 58 a of surface 52, such thatas crankpin 24 rotates in a clockwise direction as shown in FIG. 8,second rod element 28 b tends to rotate, at least initially, in acounterclockwise direction on pin 46, and pin 46 begins to move towardthe right. By virtue of being attached to pin 46, proximate end 42 offirst rod element 28 a also moves to the right. Nevertheless, by virtueof follower 54 a following curvilinear portion 58 a of surface 52, pin46 moves slightly upward. As a result, proximate end 42 of first rodelement 28 a moves slightly upward. Thus, although radial axis RA hasrotated 15 degrees past first stroke termination angle θ₁, piston 16 hasnot moved downward relative to cylinder 14. Indeed, according to someembodiments, piston 16 may move slightly upward (e.g., to a positionbetween about 0.002 inch and about 0.003 inch upward relative to thepiston 16's position at 0 degrees). (See the Table below showing anexemplary relationship for exemplary engine 10 between radial axis RA'sangle and piston 16's displacement relative to zero degrees past firststroke termination angle θ₁.)

TABLE RADIAL AXIS RA ANGLE VS. PISTON DISPLACEMENT RELATIVE TO ZERODEGREES Crank Piston Angle Depth 0 0.000 4 0.000 8 −0.002 12 −0.003 16−0.002 20 0.000 24 0.003 28 0.020 32 0.056 36 0.049 40 0.050 44 0.119 480.222 52 0.338 56 0.462 60 0.590 64 0.720 68 0.852 72 0.987 76 1.124 801.262 84 1.400 88 1.538 92 1.674 96 1.808 100 1.939 104 2.066 108 2.190112 2.309 116 2.423 120 2.532 124 2.636 128 2.733 132 2.824 136 2.908140 2.989 144 3.070 148 3.150 152 3.231 156 3.318 160 3.414 164 3.532168 3.692 172 3.816 176 3.894 180 3.897

Referring to FIG. 9, which shows crankshaft 20 in an orientation whereradial axis RA has rotated 31 degrees past first stroke terminationangle θ₁, follower 54 a of second rod element 28 b remains in contactwith exemplary curvilinear portion 58 a of surface 52, such that ascrankpin 24 rotates clockwise, second rod element 28 b continues torotate in the counterclockwise direction on pin 46, and pin 46 begins tomove slightly downward and toward the right as shown. In addition,second follower 54 b has come into contact with second curvilinearportion 58 b of surface 52. By virtue of being attached to pin 46,proximate end 42 of first rod element 28 a also moves to the right. As aresult, proximate end 42 of first rod element 28 a moves slightly to theright. Thus, when radial axis RA has rotated 31 degrees past firststroke termination angle θ₁, piston 16 has moved downward relative tocylinder 14 only between about 0.020 inch and about 0.056 inch in theexemplary embodiment shown.

As shown in FIG. 10, radial axis RA has rotated 45 degrees from firststroke termination angle θ₁. Follower 54 a of second rod element 28 bhas moved out of contact with curvilinear portion 58 a, such that onlysecond follower 54 b is in contact with surface 52 at second curvilinearportion 58 b, and second rod element 28 b continues to rotate in thecounterclockwise direction on pin 46. Pin 46 begins to move to the leftas shown (note that pin 46 cannot be seen in FIG. 10 because it ishidden by second limit member 64 as shown). Proximate end 42 of firstrod element 28 a also moves to the left. As a result, when radial axisRA has rotated 45 degrees past first stroke termination angle θ₁, piston16 has moved downward relative to cylinder 14 only between about 0.119inch and about 0.222 inch in the exemplary embodiment shown. This amountof travel, when viewed in light of the entire stroke length of theexemplary embodiment shown (i.e., about 3.897 inches when radial axis RAhas rotated 180 degrees past first stroke termination angle θ₁), resultsin an exemplary delay of the initiation of the power stroke of piston16.

Referring to FIG. 11, radial axis RA has rotated 60 degrees past firststroke termination angle θ₁, and follower 54 a of second rod element 28b remains out of contact with curvilinear portion 58 a. Second follower54 b remains in contact with surface 52 at second curvilinear portion 58b, but begins to travel downward as shown. Second rod element 28 b,rather than continuing to rotate in the counterclockwise direction onpin 46, has rotated very little and has begun to travel downward onsecond curvilinear portion 58 b of surface 52. Thus, proximate end 42 offirst rod element 28 a also begins to move downward significantly. As aresult, when radial axis RA has rotated 60 degrees from first stroketermination angle θ₁, piston 16 has moved downward relative to cylinder14 about 0.590 in the exemplary embodiment shown. Thus, whereas duringthe first 45 degrees of rotation of radial axis RA past first stroketermination angle θ₁, piston 16 traveled downward only between about0.119 inch and about 0.222 inch, during the next 15 degrees of rotationof radial axis RA, piston 16 travels roughly twice as far down cylinder14 (i.e., during only a third as much rotation of radial axis RA).

As shown in FIG. 12, radial axis RA has rotated 90 degrees past firststroke termination angle θ₁, and follower 54 a of second rod element 28b remains out of contact with curvilinear portion 58 a. Second follower54 b remains in contact with surface 52 at second curvilinear portion 58b, and continues to travel downward. Second rod element 28 b continuesto not rotate appreciably, and continues to travel downward with secondfollower 54 b contacting second curvilinear portion 58 b of surface 52.As a result, when radial axis RA has rotated 90 degrees past firststroke termination angle θ₁, piston 16 has moved downward relative tocylinder 14 between about 1.538 inches and about 1.674 inches in theexemplary embodiment shown.

As shown in FIG. 13, radial axis RA has rotated 120 degrees past firststroke termination angle θ₁, and follower 54 a of second rod element 28b remains out of contact with curvilinear portion 58 a. Second follower54 b remains in contact with surface 52 at second curvilinear portion 58b, and continues to travel downward as shown. Second rod element 28 bcontinues to not rotate appreciably, and continues to travel downwardwith second follower 54 b contacting second curvilinear portion 58 b ofsurface 52. As a result, when radial axis RA has rotated 120 degreespast first stroke termination angle θ₁, piston 16 has moved downwardrelative to cylinder 14 about 2.532 inches in the exemplary embodimentshown.

Referring to FIG. 14, radial axis RA has rotated 174 degrees past firststroke termination angle θ₁, and follower 54 a begins to contact secondcurvilinear portion 58 b of surface 52, and second follower 54 b ridesagainst third portion 58 c of surface 52. As a result, second rodelement 28 b begins to rotate in the clockwise direction.

In addition, travel limit assembly 60 begins to affect travel of piston16. In particular, in the exemplary embodiment shown, as crankpin 24moves left, as shown, both of followers 54 a and 54 b of second rodelement 28 b begin to disengage surface 52, and as radial axis RArotates past 180 degrees and followers 54 a and 54 b move away fromsurface 52, motion of second rod element 28 b may become unconstrained.Thus, exemplary travel limit assembly 60 may be provided and configuredto confine travel of piston 16 between an extended limit and acontracted limit.

For example, as shown in FIG. 14, as radial axis RA approaches 174degrees past first stroke termination angle θ₁, extension 84 of secondlimit member 64 extends further into tubular portion 74 in a telescopingmanner until an end of tubular portion 74 abuts stop 86 of second limitmember 64. This, in turn, prevents piston 16 from traveling further downcylinder 14 than a contracted limit. This also prevents second rodelement 28 b from continuing to rotate in the clockwise direction andinto a position below crankpin 24 as shown. As a result, when radialaxis RA has rotated 174 degrees past first stroke termination angle θ₁,as shown in FIG. 14, piston 16 has moved downward relative to cylinder14 between about 3.816 inches and about 3.894 inches.

As shown in FIG. 15, radial axis RA has rotated 180 degrees past firststroke termination angle θ₁ (i.e., at a second stroke termination angleθ₂, which corresponds to the end of the power stroke) and followers 54 aand 54 b have moved out of contact with surface 52, as second rodelement 28 b moves to the left as shown. Thus, only travel limitassembly 60 is preventing piston 16 from continuing to travel downwardin cylinder 14 past its contracted limit (sometimes referred to as the“bottom” of its stroke). As a result, when radial axis RA has rotated180 degrees past first stroke termination angle θ₁, piston 16 has moveddownward relative to cylinder 14 about 3.897 inches in the exemplaryembodiment shown.

As shown in FIG. 16, radial axis RA has rotated 270 degrees past firststroke termination angle θ₁, and thus, crankpin 24 has traveled to theleft and upward as shown. Second rod element 28 b continues to be out ofcontact with surface 52 and also moves to the left and upward, followingthe motion of crankpin 24 and continuing to be constrained by travellimit assembly 60, with the end of tubular portion 74 abutting againststop 86 of second limit member 64. Thus, any downward load on piston 16as piston 16 travels upward is taken by travel limit assembly 60, whichserves to push piston 16 upward, as shown, by virtue of being drivenupward by crankpin 24.

Referring to FIG. 17, radial axis RA has rotated 360 degrees past firststroke termination angle θ₁, and thus, crankpin 24 has traveled back tofirst stroke termination angle θ₁. With radial axis RA in thisorientation, piston 16 has returned to its upper position withincylinder 14, or its extended limit. Follower 54 a of second rod element28 b has returned to contact exemplary curvilinear portion 58 a ofsurface 52. Thus, the motion of second rod element 28 b becomesconstrained by surface 52. The end of tubular portion 74 of first limitmember 62 continues to abut stop 86 of second limit member 64. However,as shown in FIG. 8, as radial axis RA moves past first stroketermination angle θ₁, extension 84 of second limit member 64 begins topull slightly out of tubular portion 74 in a telescoping manner. Asshown in FIGS. 9-13, extension 84 of second limit member 64 continues tobe partially pulled out of tubular portion 74, as radial axis RAcontinues from 31 degrees past first stroke termination angle θ₁, untilradial axis RA approaches about 180 degrees past first stroketermination angle θ₁ (see FIGS. 14 and 15).

In this exemplary manner, the effective length of connecting rod 28 isvariable, such that the distance between the center of pin 38, whichoperably couples connecting rod 28 to piston 16, and the center ofcrankpin 24 is variable. For example, the distance between first endaperture 32 of distal end 30 of first rod element 28 a, and the centerof aperture 50 of proximate end 44 of second rod element 28 b isvariable (see, e.g., FIGS. 6-15), the variability of the effectivelength being facilitated in the exemplary embodiment by virtue of firstrod element 28 a and second rod element 28 b being pivotally coupled toone another. Specifically, as radial axis RA rotates between firststroke termination angle θ₁ and 180 degrees past first stroketermination angle θ₁ (i.e., to second stroke termination angle θ₂), theeffective length initially increases, thereby delaying initiation of thepower stroke, for example, until radial axis RA reaches a point 45degrees past first stroke termination angle θ₁ in the exemplaryembodiment shown. Thereafter, the effective length decreases as radialaxis RA continues to rotate toward an orientation 180 degrees past firststroke termination angle θ₁.

According to some embodiments, the exemplary configuration and/orinteraction can be tailored to achieve desired performancecharacteristics of exemplary engine 10, such as, for example, improvedefficiency, improved power output, improved responsiveness, and/orimproved torque. For example, the configuration of first rod element 28a, second rod element 28 b, followers 54 a and/or 54 b, and/orcross-sectional profile 56 of surface 52 may be tailored to improveefficiency and/or power of exemplary engine 10, for example, by changingat least one of the timing and magnitude of the delay of initiation ofthe power stroke.

According to some embodiments, initiation of the power stroke ofexemplary engine 10 may be delayed until crankshaft 20 has rotated atleast about 15 degrees beyond the first stroke termination angle θ₁. Inother embodiments, initiation of the power stroke may be delayed untilcrankshaft 20 has rotated at least about 30 degrees beyond the firststroke termination angle θ₁ (e.g., at least about 40 or 45 degreesbeyond the first stroke termination angle θ₁. In other embodiments,rotation may be set to about 25 or 35 degrees beyond the first stroketermination angle θ₁, for example, to achieve a desired performancecharacteristic of engine 10.

Exemplary engine 10, may be incorporated into a power train, forexample, including a transmission operably coupled to engine 10 and adrive member configured to perform work, the drive member being operablycoupled to the transmission. For example, the drive member may include apropulsion device, such as, for example, a wheel or a propeller.According to some embodiments, such a power train may include agenerator configured to convert rotational power into electrical power,the generator being operably coupled to exemplary engine 10. Such apower train may include a power storage device (e.g., one or morebatteries) operably coupled to the generator and configured to storeelectrical power. According to some embodiments, the transmission mayinclude one or more electric motors.

Moreover, exemplary engine 10 may be incorporated into a vehicleincluding a transmission operably coupled to engine 10 and a drivemember configured to perform work and being operably coupled to thetransmission. For example, the drive member may include a propulsiondevice, such as, for example, a wheel or a propeller. For example, thevehicle may be a car, van, truck, boat, ship, train, or air vehicle.Such a vehicle may include exemplary engine 10 operably coupled to agenerator configured to convert rotational power into electrical power,and a power storage device operably coupled to the generator andconfigured to store electrical power. The transmission may be, forexample, an electric motor.

At least some portions of exemplary embodiments of the systems outlinedabove may used in association with portions of other exemplaryembodiments. Moreover, at least some of the exemplary embodimentsdisclosed herein may be used independently from one another and/or incombination with one another and may have applications to internalcombustion engines not disclosed herein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structures andmethodologies described herein. Thus, it should be understood that theinvention is not limited to the subject matter discussed in thedescription. Rather, the present invention is intended to covermodifications and variations.

What is claimed is:
 1. An internal combustion engine comprising: acylinder block defining a cylinder having a cylinder axis; a crankshaftdefining a crankpin, wherein the crankshaft is rotatably received by thecylinder block and rotates about a longitudinal axis; a pistonconfigured to reciprocate within the cylinder; a connecting rod operablycoupled to the piston and the crankpin, wherein the connecting rodcomprises: a first rod element comprising a first distal end and a firstproximate end, the first distal end being operably coupled to thepiston, and a second rod element comprising a second distal end operablycoupled to the first proximate end of the first rod element, and asecond proximate end operably coupled to the crankpin, wherein the firstrod element and the second rod element are pivotally coupled to oneanother, and wherein the cylinder axis intersects the longitudinal axisabout which the crankshaft rotates; and a surface associated with thecylinder block, wherein the surface and the second rod element areconfigured to affect a pivoting motion of the first rod element relativeto the second rod element.
 2. The engine of claim 1, wherein the surfaceis defined by an interior surface of the cylinder block.
 3. The engineof claim 1, wherein the surface defines a cross-sectional profile. 4.The engine of claim 1, further comprising at least one followerassociated with the second rod element, wherein the at least onefollower is configured to interact with the surface and affect thepivoting motion of the first rod element relative to the second rodelement.
 5. The engine of claim 4, wherein the at least one followercomprises two followers.
 6. The engine of claim 4, wherein the at leastone follower is coupled directly to the second rod element.
 7. Theengine of claim 1, wherein the surface defines a cross-sectionalprofile, wherein the profile is configured to improve efficiency of theengine.
 8. The engine of claim 1, wherein the surface defines across-sectional profile, wherein the profile is configured to improvepower output of the engine.
 9. The engine of claim 1, further comprisinga travel limit assembly configured to confine travel of the pistonbetween an extended limit and a contracted limit.
 10. The engine ofclaim 9, wherein the travel limit assembly comprises a first limitmember and a second limit member, wherein the first limit member isoperably coupled to at least one of the piston and the first rodelement, and the second limit member is operably coupled to the firstlimit member and the crankpin.
 11. The engine of claim 10, wherein thefirst limit member and the second limit member are coupled to oneanother such that a length of the travel limit assembly is variablebetween a minimum extent and a maximum extent.
 12. The engine of claim10, wherein the first limit member and the second limit member arecoupled to one another in a telescoping manner.
 13. The engine of claim9, wherein the first rod element is configured to provide clearance forthe travel limit assembly.
 14. The engine of claim 13, wherein the firstrod element defines space through which the first limit member passes.15. The engine of claim 1, wherein the crankpin defines a longitudinalaxis parallel to and offset by a distance with respect to thelongitudinal axis about which the crankshaft rotates, wherein a lineextending between the longitudinal axis about which the crankshaftrotates and the longitudinal axis of the crankpin defines a radial axisof the crankshaft, wherein rotation of the crankshaft results inreciprocating movement of the piston within the cylinder via theconnecting rod, the reciprocating movement defining: a compressionstroke terminating when the radial axis of the crankshaft issubstantially aligned with a longitudinal axis defined by the cylinderat a first stroke termination angle and the crankpin is locatedproximate the cylinder with respect to the longitudinal axis defined bythe crankshaft, and a power stroke terminating when the radial axis ofthe crankshaft is substantially aligned with the longitudinal axisdefined by the cylinder at a second stroke termination angle and thecrankpin is located distal the cylinder with respect to the longitudinalaxis defined by the crankshaft, and wherein the first rod element andthe second rod element are configured to pivot with respect to oneanother, such that initiation of the power stroke is delayed until afterthe radial axis of the crankshaft has passed the first stroketermination angle by a predetermined amount, the predetermined amountbeing greater than 15 degrees.
 16. The engine of claim 15, wherein thepredetermined amount is at least 30 degrees.
 17. The engine of claim 15,wherein the predetermined amount is at least 45 degrees.
 18. A powertrain comprising: the engine according to claim 1; a transmissionoperably coupled to the engine; and a drive member configured to performwork, the drive member being operably coupled to the transmission. 19.The power train of claim 18, wherein the drive member comprises apropulsion device.
 20. The power train of claim 19, wherein thepropulsion device comprises at least one of a wheel and a propeller. 21.The power train of claim 18, further comprising: a generator configuredto convert rotational power into electrical power, the generator beingoperably coupled to the engine; and a power storage device configured tostore electrical power, the power storage device being operably coupledto the generator, wherein the transmission comprises an electric motor.22. A vehicle comprising: the engine according to claim 1; atransmission operably coupled to the engine; and a drive memberconfigured to perform work, the drive member being operably coupled tothe transmission.
 23. The vehicle of claim 22, wherein the drive membercomprises a propulsion device.
 24. The vehicle of claim 22, wherein thepropulsion device comprises at least one of a wheel and a propeller. 25.The vehicle of claim 22, further comprising: a generator configured toconvert rotational power into electrical power, the generator beingoperably coupled to the engine; and a power storage device configured tostore electrical power, the power storage device being operably coupledto the generator, wherein the transmission comprises an electric motor.26. The vehicle of claim 22, wherein the vehicle comprises one of a car,van, truck, boat, ship, train, and air vehicle.